KANO (AFP) – A military offensive in northeast Nigeria that killed more than 50 Islamist rebels has destroyed four villages and left corpses scattered in bushes, with some civilians among the dead, witnesses said Tuesday.

The defence ministry has said the operation was launched in response to an attack Friday by Boko Haram insurgents on an army barracks in the town of Bama in Borno state, the epicentre of the Islamist conflict.

Residents told AFP that an unknown number of civilians also lost their lives as the military bombarded the fleeing rebels. While they reported finding scores of charred bodies in the area, many were thought to be those of Boko Haram fighters.

Area resident Karim Bunu told AFP the military onslaught “completely burnt down four villages,” specifically listing Awaram, Ali-Ali, Suwabara and Kashimri, all in Borno state.

“Civilians from the affected villages,” were among those killed, he said.

“We have never seen so much death,” added a tribal chief in the area, who asked that his name be withheld. “The bushes are littered with decomposing bodies.”

Bunu, the local chief and other residents said much of the destruction was caused by bombs dropped by fighter jets. Locals are collecting bodies and digging graves for those killed, residents added.

In a Monday statement on the operation, Olukolade said that “a good number of the insurgents escaped with bullet wounds while some have been arrested. Over 50 of them died in the course of exchange of fire with ground troops.”

Fifteen soldiers were killed during the Boko Haram raid on the barracks and “during the pursuit” of the insurgents, according to Olukolade.

The defence spokesman gave no indication that the military response caused large-scale property destruction or cost civilian lives.

Nigeria’s military has been accused of using scorched-earth tactics in campaigns against Boko Haram and not distinguishing between civilian and insurgent targets. Such accusations have however been typically denied.

According to multiple witness accounts, Boko Haram stormed the barracks before sunrise on Friday, spraying it with gunfire before torching the compound. There were reports that soldiers as well as wives and children were abducted in the raid.

The army said the Islamists had tried to escape across the border with Cameroon but were pursued through the weekend by ground troops with the support of fighter jets deployed from an air force base in Borno’s capital Maiduguri, some 60 kilometres (37 miles) away.

Borno and two neighbouring states were placed under a state of emergency in May, giving the military added powers in their bid to crush Boko Haram’s four-year uprising which has killed thousands.

The conflict has affected various parts of the north and centre of Nigeria, but the northeast has been the hit hardest, including communities near Bama, which has emerged as a hotspot in the insurgency.

Boko Haram has said it wants to create an Islamic state in Nigeria’s mainly Muslim north. The southern half of the country is mostly Christian.